財城 真寿美

Debris avalanches caused by volcano sector collapse often form characteristic depositional landforms such as hummocks. Sedimentological and geomorphological analyses of debris avalanche deposits (DADs) are crucial to clarify the size, mechanisms, and emplacement of debris avalanches. We describe the morphology of hummocks on the northeastern flank of Mt. Erciyes in Kayseri, central Turkey, likely formed in the late Pleistocene. Using a remotely piloted aircraft system (RPAS) and the structure-from-motion and multi-view stereo (SfM-MVS) photogrammetry, we obtained high-definition digital elevation model (DEM) and orthorectified images of the hummocks to investigate their geometric features. We estimated the source volume of the DAD by reconstructing the topography of the volcano edifice using a satellite-based DEM. We examined the topographic cross sections based on the slopes around the scar regarded as remnant topography. Spatial distribution of hummocks is anomalously concentrated at a certain distance from the source, unlike those that follow the distance-size relationship. The high-definition land surface data by RPAS and SfM revealed that many of the hummocks are aligned toward the flow direction of the debris avalanche, suggesting that the extensional regime of the debris avalanche was dominant. However, some displaced hummocks were also found, indicating that the compressional regime of the flow contributed to the formation of hummocks. These indicate that the flow and emplacement of the avalanche were constrained by the topography. The existing caldera wall forced the initial eastward flow to move northward, and the north-side caldera wall forced the flow into the narrow and steepened outlet valley where the sliding debris underwent a compressional regime, and out into the unconfined terrain where the debris was most likely emplaced on an extensional regime. Also, the estimated volume of 12-15 × 108 m3 gives a mean thickness of 60-75 m, which is much deeper than the reported cases of other DADs. This suggests that the debris avalanche must have flowed further downstream and beyond the current DAD extent. Assessments of the DAD incorporating the topographic constraints can provide further insights into the risk and mitigation of potential disasters in the study area.

<p> Past meteorological records are important for improving our understanding of past, present, and future climates. Imaging and digitization of historical paper-based instrumental meteorological records must be carried out before these records are lost to decay. This kind of activity called "data rescue" is now taking place at many institutions around the world. A data rescue project is underway to preserve Japanese instrumental meteorological records from the 19th century. These data were collected by foreign residents and visitors, Japanese scientists influenced by Dutch science, and by Japanese merchants. Recently, meteorological measurements taken at Mito from 1852 to 1868, and at Yokohama in 1872 and 1873 have been found. Based on instrumental records collected through this data rescue project, a warmer climate in the 1840s and 1850s around the South-eastern Kanto Region has been identified. Large year-to-year variations of winter temperatures have also been detected. </p>

<p> Climate variations in East Asia during the Little Ice Age are reconstructed using wind records together with chronicles of weather disasters in Japan and China, as well as weather observations from Okinawa in the 1850s. The results of analyses are as follows: (1) On the basis of numerous records that remain for the southern coast of Japan and the south-eastern coast of China, it appears that many rainstorm disasters occurred during the summer period in both Japan and China. They usually took place one or two months later in Japan than in China; (2) Observations in Naha show that, when air pressure drops considerably, wind speed is very high and its direction rotates. Following unusual air pressure falls in Naha, strong winds caused disasters in China or in Japan. It is thought that these events are linked to movements of typhoons; (3) Increases in windstorm damage occurred during different periods in Japan and China. This may be related to changes in atmospheric circulation. Cool summer periods are observed around 1705, 1740, 1765, 1785, 1830, and 1845. The year 1855 marks a turning point between periods with prevailing cool states and periods with prevailing warm states.</p>

<p> ルイ・テオドール・フュレ神父（1816-1900年）は，パリ外国宣教会の宣教師として極東に派遣された。日本の琉球諸島・沖縄の那覇における彼の気象観測原簿の発見は，19世紀日本の歴史気候学に新しい進展を開くものである。フュレは，1855年2月26日に沖縄の主要な港である那覇（19世紀の文献ではNafaと綴っていた）に到着した。1856年12月から1858年9月まで，彼は1日5回（午前6，10時，午後1，4，10時）の気象観測を行った。水利技師アレクサンドル・デラマーシュ（1815-1884年）は，フランス海軍兵站部によってフュレ神父に委託された気象測器の検定を行った。気象観測は，1850年代のフランスで使われていた気象観測方式に従って実施された。気圧観測データは，気圧計の読みとり値，気圧計付随温度計の読みとり値，そして温度補正した気圧の数値で記載されている。気圧データは，必要に応じて，1850年代に使われたデルクロスとハイゲンスの公式を用いて検定・補正された。この歴史的な気圧観測データを現在の那覇における気圧平年値と比較した。観測期間中の1857年5月に台風が接近通過したことが，ルイ・フュレ神父によって目撃されている。ほかにも何度か気圧の低下が観測されているが，おそらく発達した低気圧の通過によるものであろう。そうしたなかで，オランダ船ファン・ボッセが多良間諸島の近くで難破したことがあったが，船長と彼の妻や船員達は島民に救助された。その後，彼らは沖縄の那覇に移送されたが，そこで3名のフランス人宣教師と出会い，最終的に出島のオランダ交易所からバタビア（現在のジャカルタ）へと航行した。</p>

This study employs Geographical Information Systems software to develop a classification system for typhoons (TYs) affecting Japan (1951-2011) and uses that system to investigate the spatial and temporal variations of storm tracks and their connection to the location and strength of the North Pacific subtropical high (NPSH). TYs coming within a 300-km buffer zone around the four main islands of Japan (JZOI) are grouped into two main types: those that remain on the Pacific Coast (PC) and those that enter the Japan Sea (JS). Results indicate that fewer TYs enter the JZOI when the NPSH extends strongly to the west and more reach Japan when it extends to the northwest. The winds around the periphery of the NPSH affect the recurvature of TYs directing them either west towards the China Mainland or around the western edge of the high towards Japan. More importantly, during periods when greater numbers of TYs affect the PC side of Japan (PC+), the NPSH extends to the southwest. However, during periods when greater numbers of TYs affect JS side of Japan (JS+), the NPSH extends to the northwest closer to Japan. The southwest extension of the NPSH enables TYs to recurve and pass to the eastern side (PC) of Japan while the northwest extension forces TYs around or across Japan into the JS. An important finding is that the moderately different positions of the NPSH change the atmospheric circulation around Japan dramatically and affect whether TYs pass over the PC side or the JS coast side of Japan. At the interannual time scale, increased JS+ years were observed since 1980 because of the frequent occurrence of the Pacific-Japan pattern. We also found that at the interdecadal time scale, PC+ years have increased due to the southwestward extension of the NPSH since 1980.

小氷期の末期にあたる江戸時代後期には，まだ気象庁による公式の気象観測が開始されていなかったため，気象庁のデータは当時までさかのぼることができない。一方で，幕末期の函館において1859～1862 年の4年間にわたり，ロシア領事館付のロシア人医師アルブレヒトが気象測器を使用した観測記録が残存していることが分かった。この幕末期の気象観測データは，現在の函館地方気象台のデータとは観測地点や観測頻度が異なるため，その差を補正するために気温データについて均質化を実施した。幕末期の函館の気温を20 世紀の函館地方気象台の気温と比較したところ，暖候期の低温と寒候期の高温傾向がみられた。その要因として，幕末期の観測地点が，現在より海洋性の性質を示すことから，海風の影響を受けやすかったと考えられる。また，幕末期の年平均気温は，函館の最近30 年間の平年値よりも約2.0℃低く，その寒冷な傾向は幕末期から20 世紀初頭まで継続していた。

本研究では，東北地方南部に位置する山形県川西町において1830年から1980年までの151年間，古日記に記されていた天候記録にもとづいて7月の月平均日最高気温を推定し，その長期変動にみられる特徴について考察した．推定結果からは，1830年代と1860年代，および1900年代に寒冷な期間がみられ，これらの寒冷な時期が東北地方における飢饉発生時期と対応していることが明らかになった．また，20世紀後半には，1980年代から1990年代前半にかけての時期は寒冷であり，この時期の寒冷の程度は，1830年代や1900年代に匹敵する可能性があることが明らかになった．一方，温暖な時期は1850年代，1870年代～1880年代，および1920年代にみられた．1850年代前半には現在の猛暑年に匹敵する温暖な年が出現していたことが推定された．

The temperature and pressure differences between Tokyo and Nagasaki were used to reconstruct past climate conditions. January and July in each available year since the 1820s were classified into several types with characteristic sea level atmospheric pressure patterns. This results in 18 years of pre-1881 data and a continuous series thereafter. The series indicate that the warming after 1900 (after the end of the so-called Little Ice Age) and again after 1960 can at least partly be attributed to an increase in the frequency of warm circulation pattern types at the expense of cold types. The difference in nature of the shifts in circulation types that occurred in the late nineteenth century compared with that in the late twentieth centuries suggests that the mechanism behind the warming in the late nineteenth century differs from that in the late twentieth century.

We have recovered instrumental temperature and pressure observations from Tokyo covering the periods 1825-1828. 1839-1855, and 1872-1875; from Yokohama covering the periods 1860-1871 and 1874; from Osaka covering the periods 1828-1833 and 1869-1871; and front Kobe covering the periods 1869-1871 and 1875-1888. The newly recovered records contain data before the 1870s, which is a period where, until recently, no instrumental data in Japan were believed to exist. Their addition to the previous backward extension of Japanese series, as based on the recently recovered intermittent Dejima/Nagasaki series 1819-1878, implies that the nineteenth-century extension of the Japanese instrumental record no longer contains major temporal gaps. The recovered data were used for a preliminary calculation of the west-Japan temperature (WJT) series, which is a representative temperature series for the area. The existence of a warm epoch in the 1850s over W-Japan and a downward temperature trend till the early twentieth century, as previously inferred from documentary data, is confirmed from the WJT data. The pressure data implies that the temperature differences between the nineteenth and twentieth Centuries are at least partly caused by a change in atmospheric circulation. Copyright (c) 2006 Royal Meteorological Society.

Instrumental observations from Dejima (Nagasaki), Japan, taken under the responsibility of the Dutch, covering the periods 1819-28, 1845-58, and 1871-78, have been recovered. The Dejima series overlaps by six months the modern Nagasaki Observatory series, which covers 1878-present. The recovered data extend the start of the instrumental Japanese series back from 1872 to 1819, leaving major gaps during 1829-44 and 1859-71.

[1] When a study is made of past climatic variations, it is preferable to obtain as long an instrumental record as possible. In Japan, the earliest official meteorological observations by JMA (Japan Meteorological Agency) date back to Hakodate in 1872. For about 130 years, the frequency and time of daily observation has varied. This is one of the major factors in creating data inhomogeneity. Accordingly, statistical estimation has been attempted to bridge the gap in daily mean temperatures caused by the limited number of daily observations. A Multiple Linear Regression Analysis was practically applied in the estimation of the daily mean temperature. The true value obtained from 24 hourly observational values (real daily mean temperature) was compared to a derived result using only three to four plus maximum and minimum daily observed temperatures. A high correlation between real values and estimated values was proven to exist.